1. Field of the Invention
This invention relates to endoscopic surgical instruments. More particularly, this invention relates to an instrument for taking biopsy tissue samples.
2. State of the Art
Endoscopic biopsy procedures are typically performed with an endoscope and an endoscopic biopsy forceps device (bioptome). The endoscope is a long flexible tube carrying fiber optics and having a narrow lumen through which the bioptome is inserted. The bioptome typically includes a long flexible coil having a pair of opposed jaws at the distal end and manual actuation means at the proximal end. Manipulation of the actuation means opens and closes the jaws. During a biopsy tissue sampling operation, the surgeon guides the endoscope to the biopsy site while viewing the biopsy site through the fiber optics of the endoscope. The bioptome is inserted through the narrow lumen of the endoscope until the opposed jaws arrive at the biopsy site. While viewing the biopsy site through the fiber optics of the endoscope, the surgeon positions the jaws around a tissue to be sampled and manipulates the actuation means so that the jaws close around the tissue. A sample of the tissue is then cut and/or torn away from the biopsy site while it is trapped between the jaws of the bioptome. Keeping the jaws closed, the surgeon withdraws the bioptome from the endoscope and then opens the jaws to collect the biopsy tissue sample.
A biopsy tissue sampling procedure often requires the taking of several tissue samples either from the same or from different biopsy sites. Unfortunately, most bioptomes are limited to taking a single tissue sample, after which the device must be withdrawn from the endoscope and the tissue collected before the device can be used again to take a second tissue sample. The single-sample limitation of most bioptomes is due to the limited space between the biopsy forceps jaws. Several attempts have been made to provide an instrument which will allow the taking of several tissue samples before the instrument must be withdrawn and the samples collected. Problems in providing such an instrument include the extremely small size required by the narrow lumen of the endoscope and the fact that the instrument must be flexible in order to be inserted through the lumen of the endoscope. Thus, several known multiple sample biopsy instruments are precluded from use with an endoscope because of their size and rigidity. These include the xe2x80x9cpunch and suction typexe2x80x9d instruments disclosed in U.S. Pat. No. 3,989,033 to Halpern et al. and U.S. Pat. No. 4,522,206 to Whipple et al. Both of these devices have a hollow tube with a punch at the distal end and a vacuum source coupled to the proximal end. A tissue sample is cut with the punch and suctioned away from the biopsy site through the hollow tube. It is generally recognized, however, that suctioning tissue samples through a long narrow flexible bioptome is extremely difficult and fraught with problems.
Efforts have been made to provide a multiple sampling ability to an instrument which must traverse the narrow lumen of an endoscope. These efforts have concentrated on providing a cylindrical storage space at the distal end of the instrument wherein several tissue samples can be accumulated before the instrument is withdrawn from the endoscope. U.S. Pat. No. 4,651,753 to Lifton, for example, discloses a rigid cylindrical member attached to the distal end of a first flexible tube. The cylindrical member has a lateral opening and a concentric cylindrical knife blade is slidably mounted within the cylindrical member. A second flexible tube, concentric to the first tube is coupled to the knife blade far moving the knife blade relative to the lateral opening in the cylindrical member. A third flexible tube having a plunger tip is mounted within the second flexible tube and a vacuum source (a syringe) is coupled to the proximal end of the third tube. A tissue sample is taken by bringing the lateral opening of the cylindrical member upon the biopsy site, applying vacuum with the syringe to draw tissue into the lateral opening, and pushing the second flexible tube forward to move the knife blade across the lateral opening. A tissue sample is thereby cut and trapped inside the cylindrical knife within the cylindrical member. The third flexible tube is then pushed forward moving its plunger end against the tissue sample and pushing it forward into a cylindrical storage space at the distal end of the cylindrical member. Approximately six samples can be stored in the cylindrical member, after which the instrument is withdrawn from the endoscope. A distal plug on the cylindrical member is removed and the six samples are collected by pushing the third tube so that its plunger end ejects the samples.
The device of the Lifton patent suffers from several recognizable drawbacks. First, it is often difficult to obtain a tissue sample laterally of the device. Second, in order to expedite the obtaining of a lateral sample, a syringe is used to help draw the tissue into the lateral opening. However, this causes what was once a two-step procedure (position and cut), to become a three-step procedure (position, suction, cut). In addition, the use of a syringe requires an additional hand. Third, the Lifton patent adds a fourth step to the biopsy procedure by requiring that the tissue sample be pushed into the storage space. Thus, in all, the Lifton patent requires substantial effort on the part of the surgeon and an assistant and much of this effort is involved in pushing tubes, an action which is counter-intuitive to classical biopsy sampling. The preferred mode of operation of virtually all endoscopic tools is that a gripping action at the distal end of the instrument is effected by a similar action at the proximal end of the instrument. Classical biopsy forceps jaws are closed by squeezing a manual actuation member in a syringe-like manner.
A more convenient endoscopic multiple sample biopsy device is disclosed in U.S. Pat. No. 5,171,255 to Rydell. Rydell provides a flexible endoscopic instrument with a knife-sharp cutting cylinder at its distal end. A coaxial anvil is coupled to a pull wire and is actuated in the same manner as conventional biopsy forceps. When the anvil is drawn into the cylinder, tissue located between the anvil and the cylinder is cut and pushed into a storage space within the cylinder. Several samples may be taken and held in the storage space before the device is withdrawn from the endoscope. While the device of Rydell is effective in providing a multiple sample tool where each sample is obtained with a traditional two-step procedure (position and cut), it is still limited to lateral cutting which is often problematic. Traditional biopsy forceps provide jaws which can grasp tissue frontally or laterally. Even as such, it is difficult to position the jaws about the tissue to be sampled. Lateral sampling is even more difficult.
Related application Ser. No. 08/189,937 discloses an endoscopic multiple sample bioptome having a hollow outer member and an axially displaceable inner member extending therethrough. The proximal ends of the outer and inner members are coupled to an actuator for axially displacing one relative to the other. The distal end of the outer member is coupled to one of a cylinder having a sharp distal edge and a jaw assembly, while the distal end of the inner member is coupled to the other. The jaw assembly includes a pair of opposed, preferably toothed, jaw cups each of which is coupled by a resilient arm to a base member. The resilient arms are bent to urge the jaws away from each other. The base member is mounted inside the cylinder and axial movement of the jaw assembly and cylinder relative to each other draws the resilient arms into the cylinder and brings the jaw cups together in a biting action. Depending on the geometry of the resilient arms, however, when the cylinder is moved over the arms, they may tend to bow inward and prevent a complete closing of the jaws. This results in a less than optimal biting action.
Related application Ser. No. 08/412,058 discloses an endoscopic multiple sample bioptome having enhanced biting action where the biting force at the jaws is substantially increased. In some cases, however, too much biting force at the jaws may be undesirable.
It is therefore an object of the invention to provide an endoscopic bioptome which has controlled jaw engagement and biting force.
It is also an object of the invention to provide an endoscopic multiple sample bioptome of controlled jaw engagement and biting force which is easy to operate.
In accord with these objects which will be discussed in detail below, the endoscopic bioptome of the present invention includes a relatively long flexible coil having a lumen with an axially displaceable wire extending therethrough. The proximal ends of the flexible coil and wire are coupled to a manual actuation means for axially displacing one of the flexible coil and wire relative to the other. According to a first embodiment of the invention, the distal end of the flexible coil is coupled to a jaw assembly and the distal end of the wire is coupled to a cylinder which is slidable over the jaw assembly. The wire is also provided near the distal end with a coaxial stopping band. The jaw assembly includes a pair of jaws each having a distal jaw cup having a proximal neck and a relatively narrow bent resilient mounting arm. The mounting arm of each jaw is coupled to the distal end of the coil by a washer (or retaining sleeve) through which a hollow threaded screw is threaded into the coil. The distal end of the wire extends through the hollow threaded screw and is coupled to the cylinder which is slidable over the jaw assembly. Axial movement of the wire relative to the coil moves the cylinder over the bent resilient arms of the jaws and over the necks of the jaw cups, thereby forcing the jaw cups together in a biting action. However, axial movement of the wire is limited by the coaxial stopping band which is arranged to abut the hollow screw as soon as the jaws close. The distance between the stopping band and the proximal end of the hollow screw is preferably equal to the distance between the distal end of the cylinder and the point on the jaw cups where the distal end of the cylinder lies when the jaws are closed.
According to a second embodiment of the invention, the distal end of the coil is coupled to a cylinder and the distal end of the wire is coupled to a jaw assembly which is slidable into and out of the cylinder. The jaw assembly includes a pair of opposed jaw cups, each of which is coupled by a narrow arm to a base member which resides inside the cylinder. The narrow arm of each jaw is a resilient member which includes a portion which is bent away from the longitudinal axis of the cylinder in order to locate the jaw cups substantially apart from each other. Axial movement of one of the jaw assembly and cylinder relative to the other draws the arms of the jaws into the cylinder or moves the cylinder over the arms of the jaws to bring the jaw cups together in a biting action.
In accord with the second embodiment of the invention, the cylinder is provided with an annular stopping crimp which prevents further proximal movement of the jaw assembly (or distal movement of the cylinder) once the jaws have closed. The distance between the stopping crimp and the proximal end of the jaw assembly is preferably equal to the distance between the distal end of the cylinder and the point on the jaw cups where the distal end of the cylinder lies when the jaws are closed.
According to a third embodiment of the invention, the distal end of the coil is coupled to a jaw assembly and the distal end of the wire is coupled to a cylinder which is slidable over the jaw assembly. The jaw assembly includes a pair of jaws each having a distal jaw cup having a proximal neck and a relatively narrow bent resilient mounting arm. The mounting arm of each jaw is coupled to the distal end of the coil by a washer (or retaining sleeve) through which a hollow threaded screw is threaded into the coil. The distal end of the wire extends through the hollow threaded screw and is coupled to the cylinder which is slidable over the jaw assembly. Axial movement of the wire relative to the coil moves the cylinder over the bent resilient arms of the jaws and over the necks of the jaw cups, thereby forcing the jaw cups together in a biting action.
In accord with the third embodiment of the invention, a portion of the coil adjacent to the jaw assembly is ground to a reduced diameter and the cylinder is provided with a radially inward flange. Axial movement of the cylinder is limited by the flange which abuts the washer (or retaining sleeve) of the jaw assembly as soon as the jaws close.
According to a fourth embodiment of the invention, each jaw cup is provided a step on its outer surface which limits distal movement of the cylinder and/or proximal movement of the jaw assembly as soon as the jaws close.
Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures.